Mourinho may be badly struggling now, but he is the most successful manager in the club’s history. Sacking him for a second time really would be a permanent farewell and Abramovich is wary of making the final cut too soon.

The Russian billionaire publicly backed Mourinho early in the season, but put all the pressure on the Portuguese by making it clear results will have to improve with the current squad of players – the underlying message was the manager could not try to spend his way out of trouble in January.

Mourinho will not be short of clubs willing to give him his next job if he leaves Chelsea and the 52-year-old could even return to Real Madrid. Abramovich will be well aware how embarrassing it would be to dismiss Mourinho, only for him to succeed at another one of Europe’s top clubs.

2) The fans' feelings

Abramovich found himself accused of ignoring the Chelsea fans when he sacked Roberto Di Matteo and made unpopular Rafael Benitez interim manager.

The Stamford Bridge faithful applauded in the 16th minute of games in honour of Di Matteo, who wore the number 16 on his shirt during his playing days, and made it perfectly clear they did not want former Liverpool manager Benitez at the club.

Despite pressure mounting on Mourinho, he crucially still has the fans onside. They sang his name even when Chelsea were losing at home to Liverpool and the majority of Stamford Bridge regulars would be upset by his departure.

Chelsea supporters were delighted Abramovich swallowed his pride to bring Mourinho back to the club and would be dismayed in equal measure if he was shown the exit door so soon after winning the Premier League title.

3) The lack of short-term replacements

Perhaps the biggest and most difficult question facing Abramovich is who he would immediately replace Mourinho with if he sacks him during mid-season.

It may also be the dilemma that has bought Mourinho a bit more time after such a disastrous start to the season. The two most experienced out-of-work managers, Carlo Ancelotti and Guus Hiddink, are both well known to Abramovich.

Having been sacked just a season after winning the Double at Chelsea, Ancelotti would surely not want to return as a caretaker, while Hiddink’s reputation took a battering during his last job in charge of the Holland national team.

Brendan Rodgers knows Chelsea well, having coached at the club, but appointing another ex-Liverpool manager as interim boss may not go down well while Fabio Capello’s attempt to get himself into the reckoning is most likely to be ignored. Abramovich is also short of internal candidates, as most of Mourinho’s staff travel around with him.

4) The lack of long-term replacements

Pep Guardiola has long been the dream for Abramovich, but could he turn it into reality? Independent intermediaries have been working on trying to set up a deal for Guardiola to take over at Chelsea next summer, but Bayern Munich want to keep the Spaniard and Manchester City are also interested in bringing him to England.

Guardiola has already turned Abramovich down once in the past. Diego Simeone has achieved great success at Atletico Madrid and he already knows Diego Costa, Thibaut Courtois and Radamel Falcao well.

But the Argentine does not speak a word of English and, like Mourinho, can be a loose cannon.

Antonio Conte is admired by advisors of Abramovich and his Italy contract expires after Euro 2016, but he has never worked outside Italy. CSKA and Russia coach Leonid Slutsky could be a surprise contender and would be a dream appointment for headline writers up and down the country.

5) The money

Abramovich handed Mourinho a new four-year contract in August, worth around £10million a year, which means the Portuguese would be due a healthy pay-off if he was sacked. Chelsea have, however, learned from the last time they dismissed Mourinho and had to write a cheque for about £18m.

Since then sacked managers have been given the option of walking away with a year’s money up front, or being paid until they find another job. Either way, Abramovich would probably be looking at a compensation bill of around £10m to fire Mourinho and, while the current contracts of Guardiola and Conte may be running down, it would cost a further £15m to take Simeone from Atletico.

Abramovich can obviously afford to pay what it takes to chop and change his managers, but no successful businessman likes to spend big on failure unless they really have to.